A Species Has Gone Extinct in the Keys, and It's the Start of a Devastating Trend
Low-lying coastal areas like the Florida Keys, which are only a few feet above sea level to begin with, are particularly vulnerable to climate change-induced sea-level rise.
A new study details the first instance of a species becoming locally extinct due to the increased sea level along this precarious island chain.
Relentlessly submerged by hurricanes and king tides while being feasted on by animals in search of freshwater, the Key Largo tree cactus is a worrying glimpse into the future of similar coastal areas around the world.
Some 125,000 years ago, during the warm years between Earth’s glacial periods, water completely covered the area known today as the Florida Keys. However, coral communities flourished just below the surface, and that overlying layer of water eventually receded during the Ice Age. Reefs and sandbars became suddenly exposed, fossilizing into the sedimentary rock that now makes up one of Florida’s top vacation destinations.
But times have changed, and in the era of rising temperatures and sea levels, the water looks to reclaim the Keys once again—and that’s a problem for the many forms of life living on their shores. NASA estimates that Key West could experience up to seven feet of sea level change by 2100, and considering the fact that, 90 percent of these islands are only five feet above the water, it doesn’t take a math whiz to sense trouble.
And unfortunately, according to the Florida Museum of Natural History and scientists at Florida’s Fairchild Tropical Botanic Garden, that trouble is already here. According to a new study published in the Journal of the Botanical Research Institute of Texas, the Keys now hold the inevitable distinction of being the first area in the U.S. to witness a localized extinction event due to sea level rise.
The species in question is the Key Largo tree cactus (Pilosocereus millspaughii)—a tube-like cactus plant that can grow up to 20 feet tall. While this species can be found in parts of northern Cuba, The Bahamas, and scattered islands throughout the Caribbean, a single stand of the plant flourished on a low limestone outcrop surrounded by mangroves in the Florida Keys. First discovered in the area in 1992, the plant established itself locally thanks to a distinct layer of soil and organic matter. But in the following three decades, what can only be described as panoply of climate disasters and animal predation slowly eroded this once viable habitat.
“In 2011, we started seeing saltwater flooding from king tides in the area,” James Lange, a botanist at Fairchild and co-author on the study, said in a press statement. “That limits the amount of freshwater available to small mammals and might be related to why the herbivores targeted this cactus, but we can’t say for sure.” Because Key Largo tree cacti store water in their succulent stems, they’re prized targets for animals with little access to freshwater due to rising salinity.
But that was only the beginning of the cactus’s problems. In 2017, Hurricane Irma created a storm surge that completely flooded the strand, and two years later, king tides once again flooded the area for three months. By 2021, only six cactus stems were left. After the plants flowered one last time, the research team salvaged the plants for replanting in greenhouses. With no other known stands of the cactus in the U.S., the plant is effectively extinct throughout the country. And the fate of Pilosocereus millspaughii is only a small glimpse into the future that awaits other wildlife in similarly low-lying coastal areas.
“We are on the front lines of biodiversity loss,” George Gann, executive director for the Institute for Regional Conservation and study co-author, said in a press statement. “Our research in South Florida over the past 25 years shows that more than one-in-four native plant species are critically threatened with regional extinction or are already extirpated…more than 50 are already gone.”
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